DESCRIPTION: (Applicant's Description) The active antineoplastic agent, cisplatin, induces a complex toxicological response mechanism in tumor cells. The in vitro genotoxic activity of the drug induces lesions through DNA adduction and intrastrand cross-linkage, that may lead to cell death, or acquired drug resistance. Generally, elevated expression of phase II-linked detoxification enzymes is implicated in differential susceptibility and acquired drug resistance. The molecular basis for these responses are not fully understood. This study proposes to assess the effect of heterologous expression of aryl sulfotransferase (AST), a phase II enzyme, on the mutation profile induced by cisplatin at the hypoxanthine guanosine phosphoribosyl transferase (HGPRT) locus of transfected CHO cells lines 253J and 647V cells. Reverse transcription polymerase chain reaction analysis shows that the parent cells do not express AST. CHO cells transfected with a mammalian vector with the rat AST cDNA, stably express the enzyme. This project provides the opportunity to collaborate with Dr. Orr on his study of anguidine as a synergistic agent to potentiate the sensitivity of human bladder cancer cells to cisplatin and its analogues. Furthermore, it will give students assess to a research project on campus, with the unique opportunity for exposure to and development of skills in molecular biology techniques. The results of this study may provide a useful model for gaining more insight into the mechanisms for toxicological response to cisplatin and its analogues, for improving their therapeutic efficacy.